Water Resources – engross.in

Availability and Scarcity of Water

• ¾ of the Earth is covered with water.

• 2 billion people will face acute water Scarcity by 2025

• Most part of India will also face severe water scarcity

• There can be two types of Water Scarcity – Quantitative Scarcity and Qualitative Scarcity

• Quantitative Scarcity means not availability of water

• Qualitative Scarcity means available water is not potable.

The following are the causes of water scarcity in the World.

Only 2.5% of all water available is Fresh Water
Out of this 2.5 %, 70% is in the form of ice in the poles and in the form of glaciers.
A little less than 30% is stored in the ground water in the world’s aquifers.

Causes of Quantitative Water Scarcity in India – Natural Causes

India is the 7th largest country with a geographic area of 3.28 Million Sq. Km.
It’s share in the world’s population is 17%
But it’s share in world’s precipitation is mere 4%
Uneven distribution of rainfall over space and time is one more natural reason

Human factors responsible for Quantitative Scarcity of Water

Unequal Access among different social groups: Not all social groups have equal access to water resources. The rich and the upper-class people have easy access to water resources while the others are deprived of it.
Large and Growing Population: A place may have ample water resource. It faces water scarcity eventually, if the population in that region increase beyond a certain limit. This is the case with most of the Indian cities.
Intensive Agriculture: The growing population needs water directly for its consumption. The agricultural sector should meet the food crop demand of this growing population. The farmers take up intensive cultivation where large amount of water is necessary. It has resulted in depletion of ground water resources all over the country.
Industrialisation: After globalisation, many MNCs have set up their industries in India. These industries require water directly and indirectly. They need water as raw material, cooling agent and to keep the industrial complex clean. The industries require continuous power supply. 22% of all electricity produced in India comes from Hydro Electric power stations.
Urban Lifestyle: Large and populous urban centres have contributed heavily to depletion of water resources. The reckless use of water by many in urban centres has only aggravated the situation.
Hydraulic Structures in Ancient India
In the first century B.C., Sringaverapura near Allahabad had sophisticated water harvesting system channelling the flood water of the river Ganga.
During the time of Chandragupta Maurya, dams, lakes and irrigation systems were extensively built.
Evidences of sophisticated irrigation works have also been found in Kalinga, (Orissa), Nagarjunakonda (Andhra Pradesh), Bennur (Karnataka), Kolhapur (Maharashtra), etc.
In the 11th Century, Bhopal Lake, one of the largest artificial lakes of its time was built.
In the 14th Century, the tank in Hauz Khas, Delhi was constructed by Iltutmish for supplying water to Siri Fort area.
Multi-purpose River Valley Projects
Advantages – Why did Nehru call the Modern Dams as ‘Temples of Modern India’?
Many purposes are integrated into one Modern Dam. Hence the name Multipurpose River Valley Project.
These Multi-Purpose River Valley Projects serve many purposes.
Irrigation, generation of electricity, supplying water for domestic and industrial use, inland navigation, afforestation, recreation are some of them.
The dams would integrate development of agriculture and the village economy with rapid industrialisation and growth of the urban economy
Government of India has accorded highest priority to improve the quality of life and enhance ease of living of people especially those living in rural areas by announcing the Jal Jeevan Mission (JJM). The Goal of JJM is to enable every rural household get assured supply of potable piped water at a service level of 55 litres per capita per day regularly on long-term basis by ensuring functionality of the tap water connections. (Source: Economic Survey 2020–21, p.357)
Disadvantages of Dams
In recent years, multi-purpose projects and large dams have come under great scrutiny and opposition for a variety of reasons.
The following are those reasons
Regulating and damming of rivers affect their natural flow.
This results in excessive sedimentation in the reservoir bed and rockier bed.
This also results in reduced sedimentation flow in the downstream.
These conditions are not favourable for aquatic life.
Dams also fragment rivers. Aquatic life can’t migrate upstream for spawning.
Dams constructed in flood plains submerges vegetation that leads to decomposition over a time.
Multi-purpose projects and large dams have also been the cause of many new social movements like the ‘Narmada Bachao Andolan’ and the ‘Tehri Dam Andolan’ etc.
Local people and the tribal people are always asked to sacrifice their resources, culture, tradition and livelihood for the construction of dams.
Large farmers, industrialists and urban centres are benefitted but not the people who sacrifice for the construction of dams.
Irrigation has also changed the cropping pattern of many regions with farmers shifting to water intensive and commercial crops.
This has great ecological consequences like salinisation of the soil.
It has transformed the social landscape i.e. increasing the social gap between the richer landowners and the landless poor.
Social conflicts can also be the result of dams.
In Gujarat, the Sabarmati-basin farmers were agitated and almost caused a riot over the higher priority given to water supply in urban areas, particularly during droughts.
Inter-state water disputes are also becoming common regarding sharing the costs and benefits of the multi-purpose project.
The dams that were constructed to control floods have triggered floods due to sedimentation in the reservoir.
The multi-purpose projects can induce earthquakes, cause waterborne diseases and pests and pollution resulting from excessive use of water.

Rainwater Harvesting

Considering the drawbacks of Multi-Purpose River Valley projects and the opposition to then, the only viable alternative is Rainwater Harvesting. This is socio-economically and environmentally viable.

Traditional ways of Rainwater Harvesting

People had in-depth knowledge of rainfall regimes and soil types and developed wide ranging techniques to harvest rainwater, groundwater, river water and flood water in keeping with the local ecological conditions and their water needs.

They are as follows:

In hill and mountainous regions, people-built diversion channels like the ‘guls’ or ‘kuls’ of the Western Himalayas for agriculture.
In the flood plains of Bengal, people developed Inundation Channels to irrigate their fields.
In arid and semi-arid regions, agricultural fields were converted into rain fed storage structures that allowed the water to stand and moisten the soil like the ‘khadins’ in Jaisalmer and ‘Johads’ in other parts of Rajasthan.
‘Rooftop rain water harvesting’ was commonly practised to store drinking water, particularly in Rajasthan.
In the semi-arid and arid regions of Rajasthan, particularly in Bikaner, Phalodi and Barmer, almost all the houses traditionally had underground tanks or tankas for storing drinking water.
The tankas were part of the well-developed rooftop rainwater harvesting system and were built inside the main house or the courtyard.
They were connected to the sloping roofs of the houses through a pipe.
Rain falling on the rooftops would travel down the pipe and was stored in these underground ‘tankas’.
The first spell of rain was usually not collected as this would clean the roofs and the pipes. The rainwater from the subsequent showers was then collected.
Bamboo drip irrigation system is practiced in Meghalaya.

Interesting Facts

Rooftop rainwater harvesting is the most common practice in Shillong, Meghalaya. It is interesting because Cherapunjee and Mawsynram situated at a distance of 55 km. from Shillong receive the highest rainfall in the world, yet the state capital Shillong faces acute shortage of water. Nearly every household in the city has a rooftop rainwater harvesting structure. Nearly 15-25 per cent of the total water requirement of the household comes from rooftop water harvesting.
Tamil Nadu is the first state in India which has made rooftop rainwater harvesting structure compulsory to all the houses across the state. There are legal provisions to punish the defaulters.